Symfony 2.7 Form choice option update

[weaverryan]

Hi guys!

This replaces #5755 #5847 and should close #5179 (or at least covers most things).

Q	A
Doc fix?	yes
New docs?	yes
Applies to	2.7+
Fixed tickets	#5179

This is a big change, and I rewrote a lot. If you have time to review, I think it's best to read the published version up platform.sh and check the code for validity. You can see the code in a project that inspired all the examples here: https://github.com/weaverryan/form_choices/tree/finished.

[weaverryan]

I got the PR target wrong - will merge into 2.7.

[althaus]

@weaverryan Nice work. Especially working out the examples should be a good help. I planned to get rid off that Status stuff as this only lead to confusion being a too constructed example.

Could you talk to @webmozart? I had some trouble understanding the choice_loader so I just took his comment from the code about partially loading stuff. In addition deprecating the choice_list, but still using it, is strange.

[althaus]

Oh... one important thing I missed: It's important to state the usage of choice_value to get around the BC* that the form options get rendered with integer based values instead of the key value. This breaks any JS frontend code relying on the keys.

(*) This is still a real BC in 2.7 in my eyes and I'm not alone. 👎

[javiereguiluz]

Since Symfony 3.0 will be released in 4 weeks, we should not use the future tense to make this article future-proof:

In Symfony 3.0, ``choices_as_values`` option isn't defined, but it's behavior is always used:

[weaverryan]

@althaus Yes, the Status isn't a great example - I removed most of them, replaced with DateTime.

I added a note about the choice_value BC break thing. Yes, this is a BC break, but no it won't be fixed (fixing it now would be another BC break). All we can do is document it well - I added a small note, I hope it's obvious enough.

About choice_loader, what do you mean by:

In addition deprecating the choice_list, but still using it, is strange.

Where is it still used? I'm also not totally clear on the use-case of choice_loader. From looking at the issue queue, I was surprised by how many people seemed to use choice_list - I'm not sure of what it's use-case is either.

Anyways, thanks for the review! We have a lot to do, so I'm merging this now - a bit faster than normal. IF anyone sees any issues, please let me know!

Thanks!

[althaus]

Yes, this is a BC break, but no it won't be fixed

I know and it's ok. It's just my rage about the decision been made. ;-)

to use choice_list - I'm not sure of what it's use-case is either.

We've used ChoiceLists in all the cases where our entities aren't coming from the database, but other sources: Printers coming from CUPS, files from the file system, config options from another backend etc. It simply was a convenient way to map those to choices. Those have to be rewritten using the choice_value/label/foo settings or with a ChoiceLoader now.

In addition deprecating the choice_list, but still using it, is strange.

Where is it still used?

Sorry, that wasn't well written. What I meant is: Although the option choice_list itself is deprecated, it's used internally for a lot of stuff (see Symfony\Component\Form\ChoiceList). It's just an understanding thingy. It's like only the cool kids are allowed to play with those toys. ;-)

I'm also not totally clear on the use-case of choice_loader

The ChoiceLoader allows to read the options from some backend service. The whole entity form type for example relies on a DoctrineChoiceLoader.

[OskarStark]

would use $categoryhere instead of $val or $cat

[OskarStark]

...but not here and in some other examples? shouldn't it be consistent?

[weaverryan]

This has already been merged (but I forgot to close the PR). But @OskarStark I will make your tweaks right now - thx :).

@althaus would you be willing to bootstrap an example using ChoiceLoader? I "kind of" understand the use-case, but it still seems like you'd need to inject (for example) the EntityManager into your FormType in order to create the ChoiceLoader that you'd pass to your form field. That seems very much not different than injecting the EntityManager in order to just make the choices manually. It seems there's more - related to "partially loading" the choices (as you eluded to). Perhaps the choices aren't fully loaded until/unless you render them? And on submit, it only loads the one choice from the database (for example)? That indeed would be interesting.

[OskarStark]

👍 @weaverryan thank you

[althaus]

@weaverryan I can try to take a look at our code and see if I can extract a use case essence of it.

It seems there's more - related to "partially loading" the choices (as you eluded to).

I took the "partial" stuff from @webmozart's code comments in the ChoiceLoader file. Never used it myself.

[althaus]

@weaverryan When will this be online? Neither 2.7 nor 3.0 branch show any changes. :(

[weaverryan]

@javiereguiluz is there a problem deploying the docs? This was merged 11 days ago, but @althaus is right - I don't see it on the site.

[xabbuh]

@althaus It's now there: http://symfony.com/doc/2.8/reference/forms/types/choice.html

[althaus]

@xabbuh Thanks for taking care. 👍